Device for protocol conversion from Ethernet to RS485 field bus

A RS485, field bus technology, applied in the field of circuit conversion devices, can solve the problem of not supporting ring or star network, etc., to achieve the effect of improving robustness and effective redundant configuration
CN102710618AInactive Publication Date: 2012-10-03王可中 +1
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
王可中
Publication Date
2012-10-03
Estimated Expiration
Not applicable · inactive patent

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Abstract

The invention discloses a device for protocol conversion from Ethernet to an RS485 field bus. The device comprises more than two CPU (central processing unit) control modules, multiple RS485 interface modules and two Ethernet switch modules; each Ethernet switch module is respectively connected with each CPU control module; the multiple CPU control modules form a CPU redundancy system, only one CPU control module has the access control right of the field bus at any time; a CPU module and a CPLD (complex programmable logic device) module are provided in each CPU control module; multiple Uart signal output channels are arranged between the CPU module and the CPLD module; the CPLD module is connected with the RS485 interface module the number of which is same as that of the uart signal channel; the CPU module has three states as follows: a master state, a standby state and a failure state, and the CPU module sends a master indicator signal and a reset signal to the CPLD module by the command control.
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Description

Technical field:

[0001] The invention relates to a circuit conversion device, in particular to a conversion device from Ethernet to RS485 field bus. Background technique:

[0002] As we all know, the RS485 bus is a serial bus, which uses differential signals to transmit on two lines A and B; generally, twisted-pair lines are used for differential transmission, so it has a strong ability to resist common-mode interference, and the sensitivity of the bus transceiver is very high. High, can detect voltage as low as 200mV, so the bus length can reach more than one kilometer. RS-485 bus network topology generally adopts a bus-type structure with terminal matching. That is, a bus is used to connect each node in series, and a ring or star network is not supported. If you need to use a star structure, you must use 485 repeaters or 485 hubs. The RS-485 / 422 bus generally supports a maximum of 32 nodes. If a special 485 chip is used, it can reach 128 or 256 nodes, and the maximum ca...

Claims

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